Drive device and image forming apparatus

Abstract

To reduce damage to gears due to backlash compared with a case in which a driving source is driven at a low speed at the start or at the stop of the driving source.SOLUTION: A driving device comprises control means (C) that controls the actuation and stop of a driving source (4), the control means (C) executing a drive mode for driving the means to be driven (B), and a backlash resolving mode for, after the drive mode is ended and the driving source (4) is stopped and before the next drive mode is started, actuating the driving source (4) by the amount of backlash between first transmission means (3) and second transmission means (2) to resolve the backlash.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a drive device and an image forming apparatus. [Background technology]

[0002] BACKGROUND ART In devices that use gears to transmit drive, the techniques described in the following Patent Documents 1 to 3 are known as techniques for dealing with backlash caused by gaps between gear teeth.

[0003] Patent Document 1, Japanese Patent Application Laid-Open No. 11-235091, describes a technique for driving a step motor at a lower rotational speed or torque than during steady state when the step motor starts or stops driving, in order to reduce noise caused by backlash.

[0004] Patent Document 2, Japanese Patent Laid-Open Publication No. 8-285050, describes a configuration in which two gears are configured with magnets having different magnetic poles and the two gears are attracted to each other by magnetic attraction, in order to reduce backlash.

[0005] Patent Document 3, Japanese Patent Laid-Open Publication No. 8-74972, describes a configuration in which inner and outer rings that come into contact with each other at a tapered edge are provided on the shaft of a neutral gear and fastened together in order to eliminate backlash in a transmission. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-235091 ("0007"-"0010") [Patent Document 2] JP-A-8-285050 ("0007"-"0009", Figure 1) [Patent Document 3] Japanese Patent Application Laid-Open No. 8-74972 ("0012"-"0014", Figures 1 and 2) Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has as its technical object to suppress damage to gears due to backlash compared to when the drive source is driven at a low speed when started or stopped. [Means for solving the problem]

[0008] In order to solve the above technical problem, the driving device of the invention described in claim 1 is: A driving source; a first transmission means to which driving force is transmitted from the driving source; a second transmission means to which driving force is transmitted from the first transmission means; The driving force is transmitted from the second transmission means. endless strip A driven means; A control means for controlling the operation and stop of the drive source executes a drive mode for driving the driven means and a backlash elimination mode for activating the drive source by an amount corresponding to the backlash between the first transmission means and the second transmission means after the drive mode ends and the drive source stops and before the next drive mode is started, thereby eliminating the backlash. and the control means for executing the backlash elimination mode based on the drive load of the driven means. The present invention is characterized by the following features.

[0009] The invention described in claim 2 is the drive device described in claim 1, the control means for operating the drive source by an amount corresponding to the maximum backlash in one cycle of the first transmission means and the second transmission means in the backlash elimination mode; The present invention is characterized by the following features.

[0010] The invention described in claim 3 is the drive device described in claim 1 or 2, the first transmission means and the second transmission means each being constituted by a helical gear; The present invention is characterized by the following features.

[0011] The invention described in claim 4 is the drive device described in any one of claims 1 to 3, the control means for executing the backlash elimination mode after the drive source has stopped in the drive mode; The present invention is characterized by the following features.

[0012] The invention described in claim 5 is the drive device according to any one of claims 1 to 3, the control means for executing the backlash elimination mode before starting the current drive mode when the current drive mode is started after the drive source has stopped in the previous drive mode; The present invention is characterized by the following features.

[0013] The invention described in claim 6 is the drive device described in any one of claims 1 to 5, the control means for driving the drive source at a lower speed in the backlash elimination mode than in the drive mode; The present invention is characterized by the following features.

[0015] Claim 7 The invention described in claim Any of 1 to 6 In the drive device described in the control means for executing the backlash elimination mode based on the driving load which varies depending on the number of members in contact with the endless belt-shaped driven means; The present invention is characterized by the following features.

[0016] Claim 8 The invention described in claim Any of 1 to 7 In the drive device described in the control means for executing the backlash elimination mode based on the driving load which varies in accordance with the contact pressure of a member which contacts the endless belt-shaped driven means; The present invention is characterized by the following features.

[0017] In order to solve the above technical problems, Claim 9 The image forming apparatus of the invention described in image holding means for holding an image; a driven means configured as an intermediate transfer means to which an image is transferred from the image holding means; 10. A driving device for driving the driven means according to claim 1 or 8 a drive device according to any one of the preceding items; The present invention is characterized by the following features. [Effects of the Invention]

[0018] Claim 1, 9 According to the invention described in (1), damage to the gears due to backlash can be suppressed compared to when the drive source is driven at a low speed when started or stopped. Furthermore, according to the inventions set forth in claims 1 and 9, when the backlash elimination mode is necessary depending on the drive load, the backlash elimination mode can be executed. According to the invention as set forth in claim 2, backlash can be eliminated more reliably than in the case where the drive source is not operated for the maximum backlash. According to the invention as recited in claim 3, even when helical gears, which tend to be affected by backlash, are used, damage to the gears due to backlash can be suppressed.

[0019] According to the invention as set forth in claim 4, backlash can be eliminated immediately after the drive mode, and the adverse effects of backlash can be suppressed in the next drive mode. According to the invention as set forth in claim 5, the backlash can be eliminated before the current drive mode, and the adverse effects of the backlash in the current drive mode can be suppressed. According to the sixth aspect of the present invention, noise and damage can be suppressed in the backlash-elimination mode compared to when the rotation speed in the backlash-elimination mode is not lower than that in the drive mode.

[0020] Claim 7 According to the invention described in (1), the backlash elimination mode can be executed when the backlash elimination mode is required depending on the number of members that come into contact with the driven means. Claim 8 According to the invention described in (1), the backlash elimination mode can be executed when the backlash elimination mode is necessary depending on the contact pressure of the member in contact with the driven means. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram of the entire image forming apparatus according to the first embodiment. [Figure 2] FIG. 2 is an enlarged explanatory view of the visible image forming device of the first embodiment. [Figure 3] FIG. 3 is an explanatory diagram of a driving device for the intermediate transfer belt according to the first embodiment. [Figure 4] FIG. 4 is an explanatory diagram of the control unit according to the first embodiment. [Figure 5] FIG. 5 is an explanatory diagram of a flowchart of the drive control of the motor for the intermediate transfer belt according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples. To facilitate understanding of the following explanation, in the drawings, the front-to-back direction is defined as the X-axis direction, the left-to-right direction as the Y-axis direction, and the up-down direction as the Z-axis direction, and the directions or sides indicated by arrows X, -X, Y, -Y, Z, and -Z are defined as the front, rear, right, left, upper, and lower, or the front side, rear side, right side, left side, upper side, and lower side, respectively. In addition, in the figures, a circle with a "·" inside it means an arrow pointing from the back to the front of the page, and a circle with an "x" inside it means an arrow pointing from the front to the back of the page. In the following description using the drawings, illustrations of components other than those necessary for the description are omitted as appropriate to facilitate understanding. [Example]

[0023] FIG. 1 is an explanatory diagram of the entire image forming apparatus according to the first embodiment. FIG. 2 is an enlarged explanatory view of the visible image forming device of the first embodiment. In Figure 1, a copier U as an example of an image forming device has a user interface UI as an example of an operation unit, a scanner unit U1 as an example of an image reading device, a feeder unit U2 as an example of a media supply device, an image creating unit U3 as an example of an image recording device, and a media processing device U4.

[0024] (User interface UI description) The user interface UI has input buttons UIa used to start copying, set the number of copies, etc. The user interface UI also has a display unit UIb that displays the contents input by the input buttons UIa and the status of the copier U.

[0025] (Explanation of Feeder Section U2) 1, the feeder unit U2 has a plurality of paper feed trays TR1, TR2, TR3, and TR4 as examples of medium storage containers. The feeder unit U2 also has a medium supply path SH1 that picks up recording paper S as an example of an image recording medium stored in each of the paper feed trays TR1 to TR4 and transports it to the imaging unit U3.

[0026] (Explanation of the imaging unit U3 and media processing device U4) In FIG. 1, the image forming unit U3 has an image recording unit U3a that records an image on the recording paper S conveyed from the feeder unit U2 based on an original image read by the scanner unit U1. 1 and 2, a drive circuit D for the latent image forming device of the imaging unit U3 outputs corresponding drive signals at preset times to the latent image forming devices ROSy, ROSm, ROSc, and ROSk of each color Y to K based on image information input from the scanner unit U1. Below each of the latent image forming devices ROSy to ROSk, which are an example of a writing means, photosensitive drums Py, Pm, Pc, and Pk, which are an example of an image holding means, are arranged.

[0027] The surfaces of the rotating photoconductor drums Py-Pk are uniformly charged by charging rolls CRy, CRm, CRc, and CRk, respectively, which serve as an example of a charging means. Electrostatic latent images are formed on the charged surfaces of the photoconductor drums Py-Pk by laser beams Ly, Lm, Lc, and Lk, which serve as an example of latent image writing light output from the latent image forming devices ROSy-ROSk. The electrostatic latent images on the surfaces of the photoconductor drums Py-Pk are developed into toner images, which serve as an example of visible images in yellow (Y), magenta (M), cyan (C), and black (K), by developing devices Gy, Gm, Gc, and Gk, which serve as an example of a developing means. In the developing devices Gy to Gk, the developer consumed during development is replenished from toner cartridges Ky, Km, Kc, and Kk, which are examples of developer containing means. The toner cartridges Ky to Kk are detachably mounted in the developer replenishing device U3b.

[0028] The toner images on the surfaces of the photosensitive drums Py to Pk are transferred in succession to be superimposed on one another in primary transfer regions Q3y, Q3m, Q3c, and Q3k onto an intermediate transfer belt B, which is an example of an intermediate transfer means, by primary transfer rolls T1y, T1m, T1c, and T1k, which are an example of a transfer means and an example of a primary transfer device, to form a color toner image, which is an example of a multi-color visible image, on the intermediate transfer belt B. The color toner image formed on the intermediate transfer belt B is transported to a secondary transfer region Q4. When only K-color image information is recorded, only the K-color photosensitive drum Pk and developing device Gk are used, and only the K-color toner image is formed. After the primary transfer, residual developer and paper dust adhering to the surfaces of the photosensitive drums Py to Pk are removed by drum cleaners CLy, CLm, CLc, and CLk, which are an example of cleaning means for image holding means.

[0029] In the first embodiment, the photosensitive drum Pk, charging roll CRk, and drum cleaner CLk are integrated as a photosensitive unit UK for the color K, which is an example of an image carrier unit. Similarly, for the other colors Y, M, and C, the photosensitive drums Py, Pm, and Pc, the charging rolls CRy, CRm, and CRc, and the drum cleaners CLy, CLm, and CLc constitute photosensitive units UY, UM, and UC. Furthermore, a K visible image forming device UK+Gk is configured by a K photosensitive unit UK and a developing device Gk having a developing roll R0k as an example of a developer holding means. Similarly, Y, M, and C visible image forming devices UY+Gy, UM+Gm, and UC+Gc are configured by Y, M, and C photosensitive units UY, UM, and UC and developing devices Gy, Gm, and Gc having developing rolls R0y, R0m, and R0c, respectively.

[0030] A belt module BM (an example of intermediate transfer means) is disposed below the photosensitive drums Py-Pk. The belt module BM includes an intermediate transfer belt B (an example of image holding means), a drive roll Rd (an example of drive means for the intermediate transfer means), a tension roll Rt (an example of tension applying means), a walking roll Rw (an example of meandering prevention means), a plurality of idler rolls Rf (an example of driven means), a backup roll T2a (an example of opposing means), and the primary transfer rolls T1y-T1k. The intermediate transfer belt B is supported so as to be rotatable in the direction of arrow Ya. In the first embodiment, the primary transfer rolls T1y, T1m, and T1c for the Y, M, and C colors are supported so as to be able to approach and move away from the photosensitive drums Py, Pm, and Pc. In the case of multi-color printing (color printing), the primary transfer rolls T1y, T1m, and T1c for the Y, M, and C colors approach the photosensitive drums Py to Pc and sandwich the intermediate transfer belt B with a predetermined contact pressure. On the other hand, in the case of single-color printing (monochrome printing) using only black, they move away from the photosensitive drums Py to Pc.

[0031] A secondary transfer unit Ut is disposed below the backup roll T2a. The secondary transfer unit Ut has a secondary transfer roll T2b as an example of a secondary transfer means. A secondary transfer area Q4 is formed by the area where the secondary transfer roll T2b contacts the intermediate transfer belt B. A backup roll T2a as an example of an opposing means faces the secondary transfer roll T2b, with the intermediate transfer belt B sandwiched therebetween. A contact roll T2c as an example of a power supply means contacts the backup roll T2a. A secondary transfer voltage of the same polarity as the charge polarity of the toner is applied to the contact roll T2c. The backup roll T2a, the secondary transfer roll T2b, and the contact roll T2c constitute a secondary transfer unit T2, which is an example of a transfer means. The secondary transfer unit Ut in the first embodiment is configured to be movable toward and away from the intermediate transfer belt B. The secondary transfer unit Ut moves depending on the type of recording paper S being used, changing the contact pressure between the secondary transfer roll T2b and the intermediate transfer belt B. For example, when thick paper is used, the contact pressure can be weakened compared to when plain paper is used, thereby mitigating the impact when the leading edge of the thick paper enters the secondary transfer area Q4.

[0032] A medium transport path SH2 is disposed below the belt module BM. Recording paper S fed from the medium supply path SH1 of the feeder unit U2 is transported by transport rolls Ra, an example of a medium transport means, to registration rolls Rr, an example of a transport timing adjustment means. The registration rolls Rr transport the recording paper S downstream in accordance with the timing at which the toner image formed on the intermediate transfer belt B is transported to the secondary transfer area Q4. The recording paper S sent out by the registration rolls Rr is guided by a registration-side paper guide SGr and a pre-transfer paper guide SG1 and transported to the secondary transfer area Q4. The toner image on the intermediate transfer belt B is transferred by the secondary transfer device T2 to the recording paper S as it passes through the secondary transfer area Q4. In the case of a color toner image, the toner images that are primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred to the recording paper S all at once. The primary transfer rolls T1y to T1k, the secondary transfer device T2, and the intermediate transfer belt B constitute a transfer device (transfer means) T1y to T1k+T2+B of the first embodiment.

[0033] After the secondary transfer, the intermediate transfer belt B is cleaned by a belt cleaner CLB, which is an example of a cleaning means for the intermediate transfer means and is located downstream of the secondary transfer area Q4. The belt cleaner CLB removes residual matter, such as developer and paper dust, from the intermediate transfer belt B that remains untransferred in the secondary transfer area Q4.

[0034] The recording paper S onto which the toner image has been transferred is guided by a post-transfer paper guide SG2 and sent to a belt conveying device BH, which is an example of a medium conveying means. The belt conveying device BH conveys the recording paper S to a fixing device F. The fixing device F has a heating roll Fh as an example of a heating means and a pressure roll Fp as an example of a pressure means. The recording paper S is transported to a fixing area Q5, which is an area where the heating roll Fh and the pressure roll Fp come into contact. As the toner image on the recording paper S passes through the fixing area Q5, it is heated and pressed by the fixing device F and fixed. The visible image forming devices UY+Gy-UK+Gk, transfer devices T1y-T1k+T2+B, and fixing device F constitute an image recording unit U3a as an example of image forming means in the first embodiment.

[0035] A switching gate GT1, an example of a switching means, is provided downstream of the fixing device F. The switching gate GT1 selectively switches the recording paper S that has passed through the fixing area Q5 to either the discharge path SH3 or the reverse path SH4 on the media processing device U4 side. The recording paper S transported to the discharge path SH3 is then transported to the paper transport path SH5 of the media processing device U4. A curl correction member U4a, an example of a curl correction means, is disposed on the paper transport path SH5. The curl correction member U4a corrects the curl, or so-called curl, of the fed recording paper S. The curl-corrected recording paper S is discharged with the image-fixed surface of the paper facing upward by discharge rolls Rh, an example of a medium discharge member, onto a discharge tray TH1, an example of a medium discharge section.

[0036] The recording paper S conveyed to the reverse path SH4 side of the image forming unit U3 by the switching gate GT1 passes through a second gate GT2, which is an example of a switching member, and is conveyed to the reverse path SH4 of the image forming unit U3. At this time, if the recording sheet S is to be discharged with the image fixed side facing downward, the transport direction of the recording sheet S is reversed after the trailing edge of the recording sheet S passes through the second gate GT2. Here, the second gate GT2 in the first embodiment is made of a thin-film elastic member. Therefore, the second gate GT2 allows the recording sheet S transported to the reversing path SH4 to pass through as is, and then, when the recording sheet S that has passed through is reversed, that is, switched back, it is guided to the transport paths SH3 and SH5. The switched-back recording sheet S then passes through the curl correction member U4a and is discharged onto the discharge tray TH1 with the image fixed side facing downward.

[0037] The reverse path SH4 of the imaging unit U3 is connected to a circulation path SH6, and a third gate GT3 (an example of a switching means) is disposed at the junction. The downstream end of the reverse path SH4 is connected to a reverse path SH7 of the media processing device U4. The recording paper S that has passed through the switching gate GT1 and been transported to the reverse path SH4 is then transported by the third gate GT3 to the reverse path SH7 side of the media processing device U4. The third gate GT3 in the first embodiment is made of a thin-film elastic material, similar to the second gate GT2. Therefore, the third gate GT3 allows the recording paper S that has been transported along the reverse path SH4 to pass through, and then, when the recording paper S has returned after passing through, it is guided to the circulation path SH6 side.

[0038] The recording paper S transported to the circulation path SH6 is sent again to the secondary transfer area Q4 via the medium transport path SH2, where printing on the second side is performed. The elements denoted by the reference symbols SH1 to SH7 constitute the sheet transport path SH. The elements denoted by the reference symbols SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, and GT1 to GT3 constitute the sheet transport device SU of the first embodiment.

[0039] (Description of the drive unit) FIG. 3 is an explanatory diagram of a driving device for the intermediate transfer belt according to the first embodiment. In FIG. 3 , a driven gear 2, which is an example of a second transmission means, is supported at an end of a rotation shaft 1 of a drive roll Rd of an intermediate transfer belt B, which is an example of an intermediate transfer means and is an example of a driven means. The driven gear 2 in Example 1 is configured as a helical gear. A pinion gear 3, which is an example of a first transmission means, is engaged with the driven gear 2. The pinion gear 3 in Example 1 is also configured as a helical gear. Driving force is transmitted to the pinion gear 3 from a motor 4, which is an example of a drive source. The intermediate transfer belt B, the driving roll Rd, the driven gear 2, the pinion gear 3, the motor 4, and the control unit C (to be described later) constitute the driving device of the first embodiment.

[0040] (Explanation of the control unit of the first embodiment) FIG. 4 is an explanatory diagram of the control unit according to the first embodiment. In FIG. 4, a control unit (controller) C, which is an example of a control means of the copier U, has an input / output interface I / O for inputting and outputting signals from and to the outside. The control unit C also has a ROM (read-only memory) in which programs and information for performing necessary processing are stored. The control unit C also has a RAM (random access memory) for temporarily storing necessary data. The control unit C also has a CPU (central processing unit) that performs processing according to the programs stored in the ROM or the like. Therefore, the control unit C in Example 1 is configured by a small information processing device, a so-called microcomputer. Therefore, the control unit C can realize various functions by executing programs stored in the ROM or the like. The control unit C of the first embodiment receives a signal from the signal output element and outputs a signal to the controlled element to control it.

[0041] (Description of signal output elements) The control unit C receives signals from signal output elements such as sensors (not shown). (Description of controlled element) The control unit C outputs signals to controlled elements such as the primary transfer rolls T1y, T1m, and T1c, the secondary transfer roll T2b, the motor 4 for the drive roll Rd, and the power supply circuit E.

[0042] (Function of control unit C) The control unit C of the first embodiment has the following functional means (functional modules, program modules) C1 to C6. The monochrome printing determination unit C1 determines whether the image forming operation to be performed is monochrome printing or multi-color printing. The monochrome printing determination unit C1 in the first embodiment determines whether the image forming operation is monochrome printing or multi-color printing based on the input contents from the user interface UI and the results of reading the document image. The primary transfer roll approach / separation control means C2 controls the approach / separation of the primary transfer rolls T1y, T1m, and T1c for Y, M, and C colors depending on whether monochrome printing or multicolor printing is being performed. In the first embodiment, the primary transfer rolls T1y, T1m, and T1c for Y, M, and C colors are separated during monochrome printing, and the primary transfer rolls T1y, T1m, and T1c for Y, M, and C colors are brought closer together during multicolor printing.

[0043] The medium type discrimination means C3 discriminates the type of recording paper S used, that is, thin paper, regular paper, thick paper, etc. The secondary transfer roll contact pressure control means C4 controls the contact pressure in the secondary transfer area Q4 by moving the secondary transfer roll T2b according to the type of recording paper S used. In the first embodiment, when thick paper is used, the contact pressure is made weaker than when plain paper or thin paper is used.

[0044] The drive load determination unit C5 determines the drive load of the intermediate transfer belt B. The drive load determination unit C5 in the first embodiment determines the drive load based on the number of primary transfer rollers T1y-T1k and photosensitive drums Py-Pk, which are members that contact the intermediate transfer belt B. As an example, in monochrome printing, when the contact between the primary transfer rollers T1y-T1c and photosensitive drums Py-Pk of Y, M, and C and the intermediate transfer belt B is weaker, the drive load determination unit C5 determines that the drive load when stopping the motor 4 at the end of the image forming operation is lower than in multicolor printing. Furthermore, the drive load determination unit C5 in the first embodiment determines the drive load based on the contact pressure of the secondary transfer roller T2b, which is a member that contacts the intermediate transfer belt B. As an example, when thick paper is used and the contact pressure between the secondary transfer roller T2b and the intermediate transfer belt B is weaker, the drive load determination unit C5 determines that the drive load when stopping the motor 4 at the end of the image forming operation is lower than when plain paper or the like is used.

[0045] The intermediate transfer belt drive control means C6 has a drive mode control means C6A and a backlash elimination mode control means C6B, and controls the driving and stopping of the motor 4 to control the rotational driving of the intermediate transfer belt B. The drive mode control means C6A controls the drive mode, which is the operation of the motor 4 during the image forming operation. In the drive mode of the first embodiment, the motor 4 is rotated at a predetermined rotation speed for image formation.

[0046] The backlash elimination mode control means C6B controls a backlash elimination mode, which is an operation for eliminating backlash between the driven gear 2 and the pinion gear 3. The backlash elimination mode control means C6B in the first embodiment executes the backlash elimination mode after the drive mode ends and the motor 4 stops, and before the next drive mode (i.e., the next job) starts. In particular, in the first embodiment, the backlash elimination mode is executed immediately after the previous drive mode ends and the motor 4 stops. In the backlash elimination mode in the first embodiment, the motor 4 is driven for a period corresponding to the maximum backlash in one meshing cycle between the driven gear 2 and the pinion gear 3. The maximum backlash value is derived in advance through experiments, etc. At this time, in the first embodiment, the rotational speed of the motor 4 is set to a rotational speed for elimination, which is slower than the rotational speed for image formation.

[0047] Furthermore, the backlash elimination mode control means C6B in the first embodiment executes the backlash elimination mode depending on the determination result of the drive load determination means C5. For example, when the drive load is high, the intermediate transfer belt B is more likely to stop than when the drive load is low, and when the motor 4 stops, the intermediate transfer belt B and the driven gear 2 are more likely to stop quickly. Therefore, backlash due to the inertial rotation of the driven gear 2 is likely to be reduced. Therefore, in the first embodiment, the backlash elimination mode is not executed when the drive load is high. While the first embodiment illustrates a case in which the backlash elimination mode is not executed when the drive load is high, this is not a limitation. It is also possible to shorten the execution period of the backlash elimination mode when the drive load is high compared to when the drive load is low. Furthermore, in an apparatus configuration in which the drive load has little effect on the occurrence of backlash, the backlash elimination mode can be executed regardless of the drive load. Conversely, in an apparatus configuration in which a lower drive load tends to reduce backlash, it is also possible to configure the backlash elimination mode not to be executed when the drive load is low.

[0048] (Explanation of the flow chart of Example 1) Next, the control flow in the copying machine U of the first embodiment will be explained using a flow chart. FIG. 5 is an explanatory diagram of a flowchart of the drive control of the motor for the intermediate transfer belt according to the first embodiment. 5 is performed in accordance with a program stored in the control unit C. This processing is performed in parallel with various other processing of the copier U. The flowchart shown in FIG. 5 starts when the copier U is turned on.

[0049] 5, it is determined whether or not a job, which is an image forming operation, has started. If the answer is yes (Y), the process proceeds to ST2, and if the answer is no (N), ST1 is repeated. In ST2, the motor 4 is controlled in the drive mode, and then the process proceeds to ST3. In ST3, it is determined whether the job has finished. If the answer is yes (Y), proceed to ST4; if the answer is no (N), repeat ST3. In ST4, the motor 4 is stopped, and the process then proceeds to ST5. In ST5, the backlash elimination mode is executed, and then the process returns to ST1.

[0050] (Function of Example 1) In the copier U of Example 1 having the above configuration, after the motor 4 is stopped at the end of a job and before the next job is started, the backlash elimination mode is executed. Therefore, every job is started with the backlash between the driven gear 2 and the pinion gear 3 eliminated. If a job is started with backlash remaining, the teeth of the gears 2 and 3 may collide forcefully when driving starts, which may cause noise or abnormal sounds or damage to the gears 2 and 3. Therefore, in Example 1, noise caused by backlash and damage to the gears 2 and 3 are reduced compared to when the backlash elimination mode is not executed.

[0051] When the motor is decelerated to stop, as in the configuration described in Patent Document 1, the drive side runs at a low speed and the driven side runs at a high speed due to inertia, resulting in residual backlash. Furthermore, a configuration that decelerates at low speeds makes it difficult to control the speed during deceleration, requiring highly accurate motors and sensors, which increases costs. Furthermore, starting the motor at a low speed only mitigates collisions, without eliminating the backlash itself. The configurations described in Patent Documents 2 and 3 require additional components such as a magnet and a tapered fastening structure, which increases costs. In contrast to these, in the first embodiment, no additional or expensive parts are required, and damage to the gears 2 and 3 is suppressed while suppressing an increase in costs.

[0052] Furthermore, in the first embodiment, the backlash elimination mode is executed for a period corresponding to the maximum backlash, and backlash can be reliably eliminated no matter at what position or phase the gears 2 and 3 stop. Furthermore, in Example 1, gears 2 and 3 are configured as helical gears. Helical gears themselves have a configuration with little backlash, but when backlash does occur, it tends to be localized within one rotation or within the axial width of gears 2 and 3. When localized, the impact of a collision tends to concentrate at a specific location, making it more likely to be damaged. In other words, the effects of backlash tend to be significant in configurations that use helical gears. In Example 1, even when localized, backlash is eliminated in the backlash elimination mode, reducing damage.

[0053] In addition, in the first embodiment, the backlash elimination mode is executed immediately after the end of a job. It is possible to execute the mode before the start of the next job, but executing the backlash elimination mode before the start of the next job causes a problem of delaying the start of the next job. In contrast, in the first embodiment, it is possible to suppress delays in the start of jobs. The backlash elimination mode is not limited to being executed immediately after the end of a job, but can also be executed before the start of the next job, or can be configured to be executed when the printer transitions to sleep mode after the previous job is completed. Furthermore, when jobs are executed consecutively, and the motor 4 is stopped for a short period between jobs, the backlash elimination mode can also be configured not to be executed.

[0054] In addition, in the first embodiment, in the backlash elimination mode, the motor 4 is driven at a slower speed than in the drive mode. Therefore, compared to when the motor 4 is driven at a high speed, the impact caused when the gear teeth come into contact with each other during backlash elimination is suppressed. Therefore, the generation of noise and abnormal sounds during backlash elimination is suppressed, and damage to the gears 2 and 3 is suppressed. Furthermore, in the first embodiment, the backlash elimination mode is executed or not executed depending on the drive load. Therefore, in the first embodiment, when the backlash is small and the need for the backlash elimination mode is low, the backlash elimination mode is not executed. Therefore, operations that are less necessary are suppressed overall, which contributes to reducing power consumption and wear and tear on parts.

[0055] (Example of change) Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments and various modifications can be made within the scope of the gist of the present invention as set forth in the claims. Modifications (H01) to (H07) of the present invention are exemplified below. (H01) In the above embodiment, a copier U is shown as an example of an image forming apparatus, but the present invention is not limited to this and can be applied to a fax machine or a multifunction machine having multiple functions such as a fax machine, printer, and copier. Furthermore, the present invention is not limited to an image forming apparatus that develops multiple colors, but can also be configured as a single-color, so-called monochrome, image forming apparatus. Furthermore, the present invention is not limited to an image forming apparatus, but can be applied to any electronic device or mechanical device that uses a motor and gears.

[0056] (H02) In the above embodiment, the motor 4 is used to drive the intermediate transfer belt B, but the present invention is not limited to this. The present invention can be applied to any motor, such as a motor for the photosensitive drums Py to Pk, a motor for the fixing device F, or a motor for transporting the recording paper S. (H03) In the above embodiment, the intermediate transfer belt B is used as the image carrier, but the present invention is not limited to this. The present invention is also applicable to a configuration using an image carrier such as a photosensitive belt or an intermediate transfer drum. (H04) In the above embodiment, the backlash elimination mode is preferably executed for a period corresponding to the maximum backlash, but is not limited to this. Depending on the design and specifications, it can be executed for an average backlash or for a period corresponding to 70% or 80% of the maximum backlash.

[0057] (H05) In the above embodiment, helical gears are used as the gears 2 and 3, but this is not limiting. Any conventionally known gears such as spur gears and bevel gears can be used. (H06) In the above embodiment, it is desirable to rotate the motor 4 at a low speed in the backlash cancellation mode, but this is not limitative. It is also possible to rotate the motor 4 at the same speed as in the drive mode or at a higher speed. (H07) In the above embodiment, examples of fluctuations in the driving load include an increase or decrease in the number of members contacting the intermediate transfer belt B and an increase or decrease in contact pressure, but the present invention is not limited to these. It is also possible to apply the present invention to cases where the driving load fluctuates due to wear and deterioration of parts over time. [Explanation of symbols]

[0058] 2...second means of communication, 3...first means of communication, 4...Drive source, B...Driven means, intermediate transfer means, C...control means, Py, Pm, Pc, Pk...image holding means, T1y, T1m, T1c, T1k, T2b...members that come into contact with the driven means, U...Image forming device.

Claims

1. A driving source; a first transmission means to which driving force is transmitted from the driving source; a second transmission means to which driving force is transmitted from the first transmission means; an endless belt-shaped driven means to which driving force is transmitted from the second transmission means; a control means for controlling the operation and stop of the drive source, which executes a drive mode for driving the driven means, and a backlash elimination mode for operating the drive source by an amount corresponding to the backlash between the first transmission means and the second transmission means after the drive mode ends and the drive source stops and before the next drive mode starts, thereby eliminating the backlash, and which executes the backlash elimination mode based on the drive load of the driven means; A drive device comprising:

2. the control means for operating the drive source by an amount corresponding to a maximum backlash in one cycle of the first transmission means and the second transmission means in the backlash elimination mode; 2. The drive device according to claim 1, further comprising:

3. the first transmission means and the second transmission means each being constituted by a helical gear; 3. The drive device according to claim 1, further comprising:

4. the control means for executing the backlash elimination mode after the drive source has stopped in the drive mode; 4. The drive device according to claim 1, further comprising:

5. the control means for executing the backlash elimination mode before starting the current drive mode when the current drive mode is started after the drive source has stopped in the previous drive mode; 4. The drive device according to claim 1, further comprising:

6. the control means for driving the drive source at a lower speed in the backlash elimination mode than in the drive mode; 6. The drive device according to claim 1, further comprising:

7. the control means for executing the backlash elimination mode based on the driving load which varies depending on the number of members in contact with the endless belt-shaped driven means; 7. The drive device according to claim 1, further comprising:

8. the control means for executing the backlash elimination mode based on the driving load which varies in accordance with the contact pressure of a member which contacts the endless belt-shaped driven means; 8. The drive device according to claim 1, further comprising:

9. image holding means for holding an image; a driven means configured as an intermediate transfer means to which an image is transferred from the image holding means; a driving device according to any one of claims 1 to 8 that drives the driven means; An image forming apparatus comprising:

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